Abstract: The process of the present invention enables a mobile radiotelephone to operate at a 100% duty cycle while providing closed loop power control. The base station measures the signal to noise ratio of the signal from the mobile and compares that SNR with the SNR threshold values the base station has for each data rate the mobile is capable of transmitting. The base station then generates power control commands to instruct the mobile to change its power depending on the outcome of the comparisons.

Abstract: The process and apparatus of the present invention limits the output power of a radiotelephone, operating in a cellular system in the preferred embodiment. This ensures the transmitted sidebands and synthesizer phase noise remains within a certain specification. This is accomplished by power detection and a correction accumulator that together generate a gain control signal by limiting the gain adjustment to a maximum value, even when the cell site communicating with the radiotelephone is sending power turn-up commands to the radiotelephone. This process includes dynamically correcting the output level of the transmitter due to gain variations in the transmitter stages or gain control elements.

Abstract: The antenna switch of the present invention switches from a portable radio's internal antenna to an external, vehicle adapter antenna. The second antenna is part of the vehicle adapter that supplies DC power to the vehicle adapter. A 1/4-wavelength transformer couples the internal antenna to the portable radio's transceiver. Diodes couple transformer and antenna to ground. A 1/2-wavelength transformer couples the vehicle adapter to the transceiver. When the portable radio is connected to the vehicle adapter, DC power is supplied to the diodes causing them to appear as a short thus making the first transformer appear as an open circuit. This causes a signal from the transceiver to be conducted to the second antenna on the vehicle adapter.

Abstract: The filter of the present invention pre-processes signaling messages transmitted by the base station while the radiotelephone is in the idle mode. The radiotelephone informs the filter of the roam status and idle status and identity of the radiotelephone. The filter then intercepts the incoming signaling messages while the processor is in the sleep mode conserving power. When the filter detects a message requiring further processing by the processor, the filter interrupts the processor to process the message.

Abstract: The antenna element mounting of the present invention enables an antenna to be mounted between the printed circuit boards of a radio instead of along side the boards. The shielding of the printed circuit boards has an indentation along one edge of each shield. When the shields are mated, the indentations form a channel into which the antenna is mounted.

Abstract: The airborne communication system enables one or more radiotelephones to communicate with a ground based cellular radiotelephone system. In the preferred embodiment, the aircraft is equipped with a repeater that relays a signal from the airborne radiotelephone to the ground base station and vice versa. Alternate embodiments use an airborne base station to register the radiotelephones before registering them with the ground system. Alternately, the antennas on the ground could be used to form aerial cell sites by pointing the antennas upward to where the aircraft flies through the cells. The system of the present invention provides the additional benefit of enabling the ground based cellular radio systems to source a call to the aircraft radiotelephone.

Abstract: A balanced mixer is used as a switch. In digital mode, the balanced mixer receives a digital mode analog waveform and a local oscillator (L.O.). The balanced mixer mixes the waveform and the L.O. to provide a resultant output signal. In analog mode, the L.O. is modulated to contain the communication information. No analog signal is present on the port of the mixer which received the digital mode analog waveform in digital mode. The desired output of the mixer is the modulated L.O. In order to pass the L.O. through the mixer, a DC bias is applied to one of the waveform terminals of the mixer to unbalance it. A diode attenuator is added to the output of the mixer to provide scaling of the analog mode output.

Abstract: The clock signal generator of the present invention divides a higher frequency clock down to a frequency that is an uneven sub-multiple of the higher frequency. The input clock to be divided down clocks an 11-bit counter (105-110) that outputs an overflow signal to a D flip-flop (125). The D flip-flop generates a load signal that resets the counter after 1025 clock periods. The load signal also suppresses, after 1025 clock periods, the toggling of another toggle flip-flop (120) that provides a divide by two clock. By suppressing a clock pulse in the divide by two clock, every 1025 clock pulses of the higher frequency clock, the average clock frequency of the divide by two clock is reduced to an uneven sub-multiple of the higher clock frequency.